Field of the Invention
The present invention relates to a touch panel structure including a color filter and a method for manufacturing the same, and a display apparatus and a method for manufacturing the same, and more particularly, to a touch panel structure suitable for outdoor use.
Description of the Background Art
Display apparatuses including touch panels for outdoor use need to have excellent display characteristics in an environment in which an amount of incident light from the outside of the display apparatuses is high, such as use under sunlight. In other words, wiring of the touch panels needs to have characteristics of a low reflection to the incident light from the outside of the display apparatuses and of high transmittance of light from light sources for display. Meanwhile, an electrical resistance also needs to be low for responsiveness and sensitivity of touch sensors needed for the touch panels.
Further, the touch sensor is formed on one main surface opposite to the other main surface of the same substrate on which a color filter is formed, that is to say, on-cell is performed, so that a thickness of a module in the whole device can be reduced more than that in a case where a touch panel substrate is provided separately. Thus, the display apparatuses including the touch panels on which the on-cell is performed are effective in improving functions by reducing thickness and weight and effective in reducing cost by simplifying a structure.
Thus, International Patent Publication No. WO2011/065292 discloses a touch panel structure and a method for manufacturing the same as follows. The touch panel structure includes a touch sensor formed on one main surface opposite to the other main surface of the same substrate on which a color filter is formed. A transparent conductive film that has a relatively high resistance compared with metal in a display portion, has a low reflection to incident light from the outside of a display apparatus, and has high transmittance of light from a light source for display is used for wiring of the touch sensor. A metal material such as aluminum having a resistance lower than that of the transparent conductive film is used for a connection terminal portion and lead-out wires for outputting an electrode potential of a touch panel to an external circuit substrate.
Meanwhile, International Patent Publication No. WO2011/052392 describes a touch panel structure and a method for manufacturing the same as follows. The touch panel structure includes a touch sensor formed on one main surface opposite to the other main surface of the same substrate on which a color filter is formed. A metal film having a low resistance is used for wiring of the touch sensor, and the touch sensor is disposed in such a position as to overlap a portion of a display portion except for an opening in a thickness direction of a display panel so as not to shield light from a light source for display.
Further, Japanese Patent Application Laid-Open No. 2013-222123 describes a touch panel structure and a method for manufacturing the same as follows. The touch panel structure is used for wiring of the touch panel having an anti-reflection function for the purpose of disposing an anti-reflection film on aluminum alloy wiring to reduce a reflection to incident light from the outside of a display apparatus, the wiring being formed by an aluminum film, an aluminum nitride film (low-reflection film), and a transparent film as an example.
However, the touch panel structure disclosed in International Patent Publication No. WO2011/065292 is complicated, and the transparent conductive film in the display portion still has a high resistance, and thus an excellent electrical characteristic for upsizing (large screen) in particular cannot be obtained.
The touch panel structure disclosed in International Patent Publication No. WO2011/052392 needs to align the wiring of the touch panel with a light-shielding layer of the color filter, and thus the design is greatly limited.
On the other hand, the touch panel structure disclosed in Japanese Patent Application Laid-Open No. 2013-222123 includes the wiring having a low resistance, which allows the design of a thin wiring width and sufficiently satisfies optical characteristics and electric characteristics needed for the above-mentioned touch panel having a high aperture ratio.
However, as disclosed in Japanese Patent Application Laid-Open No. 2013-222123, then the touch sensor including the low-reflection wiring of aluminum (Al) is formed on the substrate on the assumption that a step of forming the color filter on the opposite surface of the substrate is subsequently performed, an alkaline developing solution and a resist stripping agent used in a step of developing the color filter damages a metal portion functioning as a connection terminal portion of an opening on the wiring of the touch panel, resulting in occurrence of faulty connections between the connection terminal portion and the wiring.
In contrast, on the assumption that the color filter is formed on the substrate first and the step of forming the touch panel structure, as disclosed in Japanese Patent Application Laid-Open No. 2013-222123, is subsequently performed, the color filter is already formed on the lower surface of the substrate when the touch panel structure is formed. Thus, the color filter is scratched during a stage adsorption and a transfer when being exposed to light in the step of forming the touch panel structure, thereby reducing yields.